Two different lines of investigation will be pursued. In the first, we will follow up our study of the visual claustrum by attempting to analyze the contribution of the claustrum to visual cortical processing. Anatomically, the synaptic connections made by claustrocortical axons will be studied by EM degeneration methods. Physiologically, the visual responses of cortical cells will be observed before, during and after reversible inactivation of the claustrum. In the second project, the earlier work on the retrograde transport of lectins in the central nervous system will be continued. We will use these tracers to study the afferents to very small regions, especially to single laminae of the lateral geniculate nucleus and single layers of visual cortex.